One sordid revelation pursues another in the gradual unravelling of the Bush administration's "extraordinary rendition" programme. This is, perhaps, because "extraordinary rendition" is a newfangled phrase for an ancient crime - aggravated kidnapping. Hardly surprising, then, that each time something trickles out, the news is always bad.

Yesterday's disclosure - reported on the front page of the Guardian, based on the latest Reprieve report - involves the Bush administration's fleet of "prison hulks". The scheme is not so different from two centuries ago, when Charles Dickens opened Great Expectations on a hulk in the Thames. Then, as now, we transported prisoners around the world to little-known places. The US has injected a modern variation to the practice: even 200 years ago, there was a general insistence that prisoners be charged with and convicted of a crime before they could be condemned to the lower decks of an aging naval ship.

In one sense, the use of ships is wholly predictable, following the Guantánamo pattern: the Bush administration planned its secret prisons to be law-free zones, totally controlled by the US, far away from prying media eyes or annoying lawyers' writs. What better place, some White House strategist no doubt suggested, than a boat in the middle of the ocean?

Indeed, in this misguided American rendition experiment, an early example involved the detention and interrogation of a terror suspect aboard a US Navy vessel in the Adriatic. The man was later rendered to Egypt for torture and, ultimately, death.

Where are these ships and what are they up to? The US government has admitted that prisoners were held aboard the USS Peleliu and the USS Bataan, both of which have been sighted in the vicinity of the UK Indian Ocean territory of Diego Garcia. Reprieve believes that the US has operated as many as 17 floating prisons since 2001.

If President Bush read a few history books, he would not be condemned to repeat so many of history's mistakes. He would know, for example, that prison hulks were one of the horrors of the American revolutionary war, when more American POWs died in British prison ships than in every battle in the war combined.

While it may take years for the US courts to reunite all the ghost prisoners with the rule of law, the issue is far clearer for the authorities in Europe: it is entirely illegal for the UK or any other European state to provide any support for kidnap ships. Indeed, in the waning days of the Bush administration, any wise European government will distance itself as rapidly and as publicly as possible from such repellent practices.

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